1. Field of the Invention
The present invention relates to methods of manufacturing nitride semiconductor light emitting devices, and more particularly, to a method of manufacturing a nitride semiconductor light emitting device using an m-plane sapphire substrate.
2. Description of the Related Art
When a nitride semiconductor light emitting device is manufactured, nitride thin films, such as a gallium nitride thin film, are c-plane (0001) nitride thin films. The c-plane nitride thin films may be grown on a c-plane sapphire substrate by using metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or hydride vapor phase epitaxy (HVPE).
The c-plane nitride thin film has polarity since a gallium layer and a nitrogen layer are repetitively stacked along the c-crystal axis, which induces an internal electric field. The internal electric field generated in the light emitting device causes a reduction in recombination of electrons and holes. Therefore, luminous efficiency of the light emitting device is reduced. Furthermore, piezoelectric polarization reduces a luminous wavelength. Therefore, it is difficult to achieve a long wavelength device.
To solve this problem, a semi-polar nitride thin film needs to be grown. However, when the c-plane sapphire substrate is used, it is difficult to grow a semi-polar plane nitride thin film. Therefore, a technique that grows a semi-polar nitride thin film by using a sapphire substrate of a non-polar plane is required. Furthermore, when a semi-polar nitride thin film is grown, high-quality crystallinity needs to be achieved to increase the reliability of the light emitting device.